Sextant.



P. H. HAMMOND.

SEXTANT.

APPLICATION FILED JUNE 20, 1913.

Patented July 11, 1916.

3 SHEETSSHEET I.

. P. H. HAMMOND.

SEXTANT.

APPLICATION FILED JUNE 20, 1913.

1,191,073. Patented July 11, 1916.

3 SHEETS-SHEET 2.

P. H. HAMMOND.

SEXTANT.

APPLICATION FILED JUNE 20. 1913.

3 SHEETS-SHEET 3- 270 w i 290 25 f i 35 ZMQSLSPSJ mania":

Patented July 11, 1916.

rmm nus'ron HAMMOND, or 'rnn UNITED'STATES. NAVY.

Specification of Letters Patent.

1 Application med June 20,1913. Serial No. 774,786. 1

' nnmca'rnn-ror'nr rus ic.

To all whom it may concern I Be it known that I, PmLIr Hos'ron He n-MOND, of the United States ,Navy, a c1t1- zenof the United States,residing at An-z napolis, in the county of Anne Arundel and State ofMaryland, have invented, or discovered certain new and usefulImprovevisions of the act of March 3, 1883,

ments in Sextants, of which the f ollowin'g is a specification,reference being hadtherein to the accompanying drawings.

This application is made under the pro- Ch. 143: 22 Stat. L.- 625, andit is understood that the invention described herein, if patented, maybe used by the Government, or any of its ofiicers or employees in theprosecution of work for the Government, or by any other person in theUnited States, without the payment tome of any royalty thereon.

This invention relates to sextants and has for its general object toprovide means whereby thegraduated limb and vernier may be convenientlyilluminated in order to facilitate the taking of nautical and'otherobservations in the dark. I

The more particular objects of the invention, together'with meanswhereby the same may be carried into eflect, will best be understoodfrom the following description ofcertain forms or embodiments thereofillustrated in the accompanying drawings. It:

will be understood, however, that the constructions described-and shownhave been chosen for illustrative purposes merely and that theinvention'may beembodiedgin other forms without departing from thespirit and scope thereof. v v

In said drawingsFigure 1 is a plan view .of a sextant having myimprovements applied thereto. Fig. 2 is a front view of the same. Fig. 3is an enlarged vertical,

sectional view taken on a plane passing through the graduated limb andvernier arm. Fig. 4 is a plan view of a portion of the graduated limb'and vernier arm showing a modified form of illuminating device. Fig. 5is a side view, partly in section, of the parts shown in Fig. 4. Fig. 6is a detail, sectional view taken substantially on the line 33, Fig. 5.Fig. 7 is a detail, perspective view of the contact members associatedwith the lamp shown in Fig. 5. V v Referring first to Figs. 1 to 3, thesextant proper may be 'of any usual or well known constructioncomprisingessentially a frame vernier 19.

12-, provided with a handle 13 and carrying a graduated are or limb 14and a horizon glass 15, a telescope 16 rigidly mounted on frame 12, anda vernier or indicator arm 17 pivoted to the frame and carrying adjacentits pivot the usual index glass 18 and adj acent 1ts outer end the usualindicator or In accordance with the present invention the usual readingglass20 is-carried by a supporting arm 21 pivoted for movement at 22 onan arm 23 which in turn is pivoted for movement on-.the upper or outerend of a post 24 projecting from the vernier arm 17.

v Patented July 11,1916.

Adjacent'the usual vernier opening 25 in the arm 17,' and supported onsaid arm, as 'bya bracket 26, is a translucent screen 27 of any suitablematerial, preferably ground glass. Supported-by the arm'21 immediatelyin the. rear of the screen 27 is an incandescent' electric lamp 28,behind which is arranged a preferably concave mirror or reflector 29carried by an arm 30 secured to the arm 21. For supplying current to thelamp,

28 there are provided wires or conductors 31 connected with said lamp inany suitable manner, extending rearwardly along the 'vernier arm 17,to'which they are preferably secured as by clips .32, and entering thehandle 13, which is formed hollow to constitute a housing for a -drybattery of any usual type with which said conductors 31 aresuitablyconnected. For controlling the current to the lamp 28 there isprovided a rod or button 33 adapted to cooperate with any suitable -orwell known form of switch or contact member within the handle '13, saidrod or button being carried by a flat spring 34, secured to the end ofsaid handle and 33 in a position to keep open-"the circuit to u thelamp, said rod or button being capable of being pushed inwardlyagainstthe resistance of said spring, for the purpose of closingsaid circuitand causing said lamp to be facilitate reading the result of saidobservation, the rod or button 33-may be ushed inlifand wardly by thethumb or finger o the grasping the handle 13, whereupon the lamp 28 willbe lighted, as above ex lained.. The

light from said lamp, reflecte and concenadapted normally to holdthe rodor button I readily observed in the dark.

I the construction of the sextant may be substantially as shown in Figs.1 to 3, or otherwise, in accordance with any usual type. As in Figs. 1to 3, 14 denotes the graduatedlimb Tn the modification shown in Figs.- 4to v or are, 17 the Vernier or indicator arm, 19

the Vernier, and the Vernier opening in the arm 17 adjacent, Vernier 19through which the graduations on the limb 14 may be observed. As in theform of the invention first described, a translucent screen 270 isarranged uponthe Vernier 'arm 17 adjacent the Vernier opening 25, and areading glass' 200 is carried by the outer end of an arm 210 pivoted toan arm 230 which in turn is pivoted to a post 240 projecting from theVernier arm 17. In this form of the invention, however, the lamp 280 andreflector 290 2 are carried'by a slide 35 mounted on the arm 210 andadapted,

to move longitudinally thereon and to be desired position. Also in thisform of the invention the current to the lamp 280 is controlled by means,of a switch comprising a pin 37 projecting from the lamp socket 38 inthe slide and an angular spring contact member 39 secured to said slide,as by means of screws 40 passing through a cap 41 and It.

through openings in one arm of said contact member 39, and entering saidslide 35. i The conductors 310 are connected respectively with the. lampsocket 38 and with the contact member 39. When it is desired to lightthe lamp 280 for the purpose of illuminating and reading the scale andVernier, the contact member 39 may be pressed inwardly against heldfrictionally in any its own resilience into contact with the end of pin37, therebyclosing the circuit to the 45 lamp. When using the instrumentin the day time, or when for any other reason the use of the lamp is notdesired, the slide 35 may be movedinwardly on the arm 210 and v out ofthe .way.

Having thus fully .described'my invention, I claim as new and desire tosecure by Let ters Patent 1. The combination with' a mathematicalinstrument provided with a' graduated scale and an indicator armadjustable relatively to the scale, the said instrumenthaving a handholdportion by held in position for use, of means for illuminating the scalecomprising an electric lamp carried by and movable with the indicatorarm, a batte arranged within the said handhold portion of, theinstrument, circuit wires leading from the battery to the lamp, and'acircuit controlling switch adjacent to the battery.

2. The combination with a mathematical instrument provided with agraduated arc, an indicator arm and a .vernier adjustable relatively totheiar'c', the said instrument having a portion shaped as a handhold torgrasping; and supporting it in position for use, of means forilluminating the are comprising an electric lamp carried by and movablewith the indicator arm, light reflecting and diffusing membersassociated with the lam a battery housed within the said handhol portionof, the instrument and in circuit with. the lamp, and a lamp controllingswitch adjacent to the battery.

In testimony whereof I aflix my signature in the presence of twowitnesses.

PHILIP HUSTON HAMMOND.

Witnesses:

EDGAR H, MAY, J. F. THORNTON.

which is grasped and

